Process of separating wax from mineral oil distillates



Feb. 9 1926.

S. H. HALL ET AL PROCESS OF SEPARATING WAX FROM MINERAL OIL DISTILLATES Filed Sept. 8. 1921 .III

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UNITED STATES 'SELDEN H. HALL, 0F POUGHKEEPSIE, NEW YORK, CYRUS HOWARD HAPGOOD, OF NUTLEY, NEW JERSEY, ASSIGNOBS TO THE DE LAVAL SEPABATOB COMPANY, OF YORK, N. Y., A CORPORATION OF NEW JERSEY.

PROCESS OF SEPABATING WAX FROM MINERAL OIL DISTILLATES.

Application ledvseptein'ber 8, 1921. Serial No. 499,825.- y

A To all 'whom #may concern: 'Be it known that we, lSELDEN H. HALL .and CYRUs lILIowAnn HAPGooD, citizens o f the United States, and residing at Poughkeepsie, county of Dutchess, State of New "ork, and Nutley,.county of Essex, State of New Jersey, respectively, have invented a new and useful Improvement in Processes of Separating Wax from Mineral Oil Distillates, of which' the 'following is a full, clear, and exact description,lreference being had to the accompanying drawings, which form a part of this specification.

n In the refining of paraiine base crude oil, it iscustomary to distill off successively products of successively higher boiling points, such as naphtha, illuminating oil, gas oil and wax distillates. These wax distillates, which are particularly adapted forthe manufacture of lubricating oils, carry,y

in solution more or less wax (paraine Whose separation from the oil is necessary or desirable. It isknown to el'ect the separation of wax from wax distillates` by bringin the `distillate in heat exchange-relation wit refrigerated brine for Vthe pur ose of throwing the wax out of solution an then separating the wax, which is in crystalline form, from the oil by filtration or settlement. These oil processes are bulk processes, involve the use of large and expensive plants, the han- ,A the separation-by no means thorough. -It

dling of a large volumev of stock at one time and the expenditureof considerable time.

The processes, moreover, are wasteful and has not been found possible, however, in

' any continuous process, to separate the wax from the oil by centrifugation and discharge the wax from the bowl unless naphtha is -v blended with the distillate. If this is done 'the wax maybe separated from the oil by centrifu ation, and the \oil..and wax separately d1scharged,.but each ingredient carries out with it a lar proportion of naphtha and both ingredients must be distilled to drive offv the naphtha. This in turn deleteriously affects the color of the treated material, which must be subsequently filtered -to'decolori-z'e. Y l

The object of the present invention is to devise a process whereby it will be possible, -without blending the distillate with naph- -tha, to centrifugally separate the oil and wax and continuously discharge the wax from the bowl.

A similar problem presents itself in .thev

separation of stearin from oleo. When a solution of oleo and stearin is subjected to a temperature suiiciently low to throw out of solution the stearin in a crystallized condition, it has beenV found possible to centrfugally separate the two and continuously discharge the stearin from this bowl by introducing into the bowl a heavy cushioning liquid (for example, water) which, in its discharge from the bowl, carries with it the crystallized stearin. Subsequent treat-- ment is required to separate the water and stearin. This may be effected by settlement in a tank in which the stearin rises to the top andcontinuously overflows, while the Water is siphoned ofi from the bottom by a pipe operating on the principle `of a Florence llask. The overliowing wax carries with it considerable water. The mixture of stearin and water must now be heated and then centrifugally separated.

Thepresent invention is equally applicable to this process in that, without the addition of an vheavy liquid that isrelied upon for cus ion'ing or sludging purposes, the stearin may be centrifugally separated and continuously discharged.`

In carrying out this process we prefer to use a centrifugal machine of the type shownv in the patent of Selden H. Hall (one in shown and accordingly a drawing, illustrating such machine 1n vertical cross-section, is herewith appended. It ,will'be understood, however, that-the execution of the process is not dependent upon the employment of any particular construction of machine. The drawing will first be explained and then the process described.

VThe bowl shell w has a bottom b with a socket o fitting the driving and supporting spindle d.. The bowl top e has a .discharge outlet f at the upper end. Extending axially of the bowl is a feed tubev g. Around the feed tube is an independent feed tube h. Within t el bowl is a liner` z' composed of a number of superimposed frustro-conical members, commonly called loa` discs, provided withvertically aligning oriices. Above the liner is a top disc j af- Jr'ording a channel for the conveyance of the heavy liquid escaping around its periphery to the outlet f. The top disc has a neck up within which the lighter separated ingredients 'travel to their outlet. The lowest disc of the liner 't' extends out relatively close tothe periphery, as does 4throw the wax outwardly, while the top disc j.

The feed tube g terminates in radially extending channels m communicating with the sets of orifices in the liner z'. The feed tube h terminates in radially extending channels fn. (closed from communication' with channels m) opening into thespace between the lower disc and the bowl bottom.

Any ingredients fed into the tube g will be delivered to the liner orifices and will pass up therein and be distributed between the discs of the liner. Any ingredients fed into the tube L will be carried direct to the periphery, and if those ingredients are heavier than the other ingredients and are free-flowing, they will remain at the periphery and travel along the bowl wall to the space above the top disc 7' and thence to the outlet f, in accordance with the description in said Hall application.

For the purposes of the present invention the feed passage it and channels n are heat-insulated from feed passage g and from the separating compartment Aof the bowl. The top disc j is also heat-insulated rom the separatin space of the bowl. This may be accomp ished by applying layers of bakelite, o to the inner wall o tube k, p to the outer wall of tube g, fr to the lower or inner face of the bottom disc of the liner e', and s to the lower or inner face of the top disc j.

The first step in the present process 1nvolves subjectin the wax distillate to a temperature suhciently low' to throw the crystalline wax out of solution. c

The refrigerated mixture of oil and wax is then `fed into the feed tube g and discharges through the channels m into the lines. of orifices in the linery i, being thence distributed throughout the spaces between the liners, centrifugal force operating to the oil is displaced inwardly.

Simultaneously with the supplying of the mixture to be separated to the bowl, hot water is fed into the feed tube It and through the channels n is carried to the periphery of the bowl. The water distributes itself over the inner wall of the bowl and constitutes an envelope for the wax which, being lighter than the water, does not penetrate the water but rests against it as a cushion.

The melting points of vary from 100 to 160Y the various waxes F. The water tertulia should be hot enough to melt the wax having the highest meltin point. The temperature of the water s Ould, therefore, be not less than about 160 F. and is preferably about 180o F.. y

The effect of the envelope of hot water is to melt the layer of wax immediately adjacent thereto so that this wax, in a fluid condition, will flow out with the water, from which it may be separated by gravity -or centrifugal force. The oil will flow out of the outlet for the lighter fluid. During the iow of the wax from the separating chamber through the discharge passage above the top disc j to the outlet f, the wax is maintained iuid by the hot water so that cooling of the wax during its flow through the discharge passage, and consequent partial solidification and clogging, are avoided. As hereinbefore explained, the insulating material applied to the disc j prevents any substantial heat exchange between the material inthe discharge passage and the material in. the separating compartment.

IBy providing theV heat-insulation described, there will be little or no exchange of heat between the water and the mixture of oil and wax during their flow through the feed passages and no exchange of heat be` tween the water and the mixture undergoing separation in the bowl. Further only the outer layer of wax adjacent the water envelope will be lnelted, the heat not penetrat- 4ing to the innerlayer of wax adjacent the oil to a degree sufficient to melt the inner layer of wax and throw it into solution with the oil.

In applying the process to the separation of stearin from oleo, the mixture should be at a tem erature of F. in order to crystallize t e stearin. The water should be' at a temperature suicient to melt the outer layer of stearin, which melts at a temperature of 122 F. .we prefer-a water temperature of about 150 F.

lIt is apparent that the invention is not limited in its application to the separation of wax from mineral oil wax distillatea, nor to the separation of stearin from oleo; these two substances of widely different characteristics being cited merely asexamples of useul applications of the process. It is clear that the process is applicable to the separation of any solid from a liquid when the solid is capable of being melted by another heavier liquid immiscible with the solid when melted, or even if miscible therewith- .if it is desired to form a solution of such heavy liquid and such solid, or if the components of such solution are readily separable by distillation or otherwise.

Nor is our invention limited to theemployment of a flowing or traveling envelope of heated heav liquid. Inasmuch as the water is not utilized for the purpose of providing an agent toisludge out the wax, stearin or other melted ingredient (such ingredient being self-discharging by reason of its v liquidity) it is suflicient to surround the mixagainst the bowl periphery or clogging on the way toward or at the outlet. Further,A

the words melt and liquefy are also not used in an absolute sense, but in a relative sense, as intended to define any condition approximating liquidity, which will make the material sufficiently free flowing to slip or slide out ofthe bowl without building up or clogging. We are aware that it is not new, in the separation of liquids from heavier solids, to utilize a still heavier liquid as a cushioning liquid to carrythe solids out of the bowl; but this process is not our .proces or evnan indispensable agent in the execution of our process, which involves an altogether different inventive conception, namely: a different temperature regulation of the solids in the bowl whereby the outer layer of solids is elevate-d in temperature to the degree required to enable it to readily discharge while the inner layer of solids is maintained at a lower temperature and sufficiently cold to avoid dissolving in the liquid.

Having now fully described our invention, what we claim and desire to protect by Letters Patent is:

1. The processof separating wax from mineral oil wax distillates, after the wax distillate solution has been refrigerated to` throw out ofsolut-ion the wax in crystalline form, which comprises subjecting the mixture of oil and wax to centrifugal force, feeding water of a temperature sufficient to melt wax contacting therewith to the periphery of the mass' of the mixture undergoing centrifugation, thereby forming a surrounding envelope of water contacting with and adapted to melt the` outer layer of wax, separately discharging the oil and the melted wax and water, and heat insulating the inflowing water and the outflowing wax and water from the m-ixture of wax andI oil.

2. The process of separating two ingrecomprises subjecting the same at a temperature which will maintain the lighter ingredient liquid and the heavier ingredient solid, together with a liquid heavier than and immiscible with the solid and having a temperature above the melting point of the solid, to centrifugal force whereby the constituents will arrange themselves in zones comprising an outer zone of the added heavy liquid, an inner zone of the lighter soluble ingredient and a middle zone ofthe heavier soluble ingredient, the relatively hot heavy liquid effecting a melting of the adjacent port-ion of the ingredient of the middle zone,

continuously inflowing said ingredients, continuously discharging the hot heavy liquid and the melted ingredient together and floating olf separately the lighter ingredient, and maintaining the hot heavy liquid out of heat-exchange relation with said lighter cold ingredient so that no portion of the heavier soluble ingredient mixed or contacting with said lighter ingredient will pass into solutiontherewith during the separating operay tion.

ture which will maintain the lighter ingredient liquid and the heavier ingredient sohd, which comprises subjecting said ingredients to the actionV of centrifugal force to effect a separation of the two ingredients, feeding a liquid heavier than either of said ingredients to the periphery of the mass of the mixture undergoing 'centrifugation and forming an envelope of such heavy liquid surrounding the solid, maintaining said heavy liquid at a temperature suflicient to melt the outer layer of solids while not sufficient to melt the inner layer of solids, and separately outflowing the light liquid and said melted solid.

4. The process of separating two ingredients the heavier of which solidiies at a higher temperature, a mixture of which has been. subjected to a temperature which will maintain the lighter ingredient liquid into an inner zone of the light ingredient and an outer zone of the heavier ingredient, and surrounding the zone of the heavier ingredient with a heated envelope adapted to liquefy its outer layer, and separately discharging the lighter 'ingredient and the thus liquefied portion of heavier ingredient.

In testimony of which invention, we have hereunto set our hands, at New York, on this 2nd day of September, 1921.

SELDEN H. HALL.

CYRUS HOWARD HAPGOOD. 

